1. Technical Field
Aspects of the present invention relate to an image processing device such as a printer, a copier, a personal computer configured to process an image and the like, which are implemented with a function to overlay a watermark one an original image.
2. Prior Art
Conventionally, image processing devices capable of overlaying a watermark image composed of character strings and/or color graphics, on an original image which is received from an external device have been known. For example, a graphic image of a company LOGO and/or character strings such as “DO NOT COPY”, “IN HOUSE USE ONLY”, “CONFIDENTIAL” may be overlaid when the original image is printed.
An example of such an image processing device is disclosed in Japanese Patent Provisional Publication No. 2000-293339 (hereinafter, referred to as '339 publication). According to '339 publication, the color and the color density of the watermark can be adjusted arbitrarily. Generally, the color density of the watermark is set to be thinner than the original image on which the watermark image is overlaid.